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Concept of effective strain in constitutive modeling of granular materials. Technical note
92A modulus, anisotropy, strain softening due to strain Iocalisation, and stress ratio during consolidation. A smooth transition from very small strain to pre-peak to post-failure behaviour is generated.
942249 Concept of effective strain in constitutive modeling of granular materials. Technical note Iai, S Soils Found V33, N2, June 1993, P171-180 The concept of effective strain, strain minus volumetric strain due to dilatancy, is proposed as a reciprocal to the concept of effective stress. Where overall volume remains constant during shearing, volume of voids can change due to particle rearrangement, and relative displacements of particles which are in contact in granular materials are,on average, consistent with respect to effective strain. Effective strain energy and Drucker's stability postulates with respect to effective strain energy are examined. It is shown how these concepts are useful in constitutive modelling of granular materials.
942250 Finite element modeling of soil-structure interaction systems: selection of hyperbolic parameters Marin, H E; Kiefer, F W; Anderson, L R Proc 29th Symposium on Engineering Geology and Geotedmical Engineering, Reno, 22-24 March 1993 P242-255. Publ Reno: University of Nevada, 1993 In many practical examples when using finite element analysis with a hyperbolic soil model to analyse soil structure interaction, it is necessary to estimate soil parameters at the design stage, as representative values will not be available until construction is underway. Hyperbolic soil parameters have been compiled for various soils by many authors, but selection of specific values for a given problem is difficult. Guidance on parameter selection is provided, based on stress-strain and bulk modulus behaviour, on the concept of incremental loading conditions prior to hyperbolic failure, on the construction sequence, and on careful analysis of results of the finite element modelling.
Design methods
942252 Grey system theory applied to rock mechanics. Technical note Cai Sijing; Tong Guangxu; Gao Hualin lnt J Rock Mech Min Sci V30, N4, Aug 1993, P473-478 The fundamentals of grey system theory, where a system is intermediate between a 'black box' (interior can be controlled but not observed) and a 'white box' (can be controlled and observed) are outlined. Grey relation analysis, tbr use when a system contains a number of parameters or factors whose interrelations are not very clear, is presented. The grey model for the examination of the mathematical relation between factors, grey system prediction, and grey decision making on the unity of event, countermeasure, and effect are described. Applications to rock engineering are briefly considered.
942253 Advanced scheduling in an opencast coal operation Simpson, H Quarry Manage Sept 1993, P23-33 Production at the Middleberg open pit coal mine in South Africa has been optimised by use of the MINESTAR Enhanced Scheduling Software Package. This program can model physical parameters and simulate production machinery. Primary short-term requirements and long-term schedules can be rapidly evaluated and a variety of options compared. The package has become a standard management tool.
942254 Reliability prediction around openings in Rock Engineering Huang Hongwei Proc EUROCK'93, Lisbon, 21-24 June 1993 V1, P129-134. Publ Rotterdam: A A Balkema, 1993 Because rock mass structures are uncertain, selection of input parameters for numerically modelling the stability of underground openings usually requires engineering judgement. An alternative approach is proposed, using in-situ measured displacements, Grey system forecasting (some rock mass parameters known, some unknown), Bayesian back analysis, and reliability analysis of the finite element method.
See also: 942439
942251 Establishing the potential behavioural modes of rock engineering systems by computer simulation of interaction matrix energy flux. Technical note Hudson, J A; Hudson, J L lnt J Rock Mech Min Sci V30, N4, Aug 1993, P457-468
942255 Practical aspects of a three-dimensional approach to tunnel data recording Howell, G C; Jooste, D E; Warwick, D W Proc TUNCON'92, Design and Construction of Tunnels, Maseru, Lesotho, September 1992 P157-162. Publ Yeoville: South African National Council on Tunnelling, 1992
The interaction matrix concept for rock engineering of Hudson (1992) is first outlined. Each leading diagonal box is associated with an energy potential and energy transfer via the mechanisms in the off-diagonal boxes is considered. A computer program has been developed to calculate and graphically display energy changes within the interaction matrix. Simulation cases are shown for regular and irregular attenuation and chaotic behaviour, with initialisation of primary variables then total step energy transfer and entropy increase for a number of steps illustrated. Practical applications of the concepts described are considered.
Use of computers in design of underground structures is now almost universal. Recent developments in 3D graphics capabilities and database programs combined with geometric design packages allow visual represenatation of many features. Traditional investigation methods have been modified for use with the new systems, for instance face mapping has been largely replaced by longwall mapping. A split map technique has been developed which allows accurate description of discontinuities without need to directly measure their dip and strike. The 3D graphic representations allow pertinent geological features to be studied at the design stage.
942249 Concept of effective strain in constitutive modeling of granular materials. Technical note Iai, S Soils Found V33, N2, June 1993, P171-180 The concept of effective strain, strain minus volumetric strain due to dilatancy, is proposed as a reciprocal to the concept of effective stress. Where overall volume remains constant during shearing, volume of voids can change due to particle rearrangement, and relative displacements of particles which are in contact in granular materials are,on average, consistent with respect to effective strain. Effective strain energy and Drucker's stability postulates with respect to effective strain energy are examined. It is shown how these concepts are useful in constitutive modelling of granular materials.
942250 Finite element modeling of soil-structure interaction systems: selection of hyperbolic parameters Marin, H E; Kiefer, F W; Anderson, L R Proc 29th Symposium on Engineering Geology and Geotedmical Engineering, Reno, 22-24 March 1993 P242-255. Publ Reno: University of Nevada, 1993 In many practical examples when using finite element analysis with a hyperbolic soil model to analyse soil structure interaction, it is necessary to estimate soil parameters at the design stage, as representative values will not be available until construction is underway. Hyperbolic soil parameters have been compiled for various soils by many authors, but selection of specific values for a given problem is difficult. Guidance on parameter selection is provided, based on stress-strain and bulk modulus behaviour, on the concept of incremental loading conditions prior to hyperbolic failure, on the construction sequence, and on careful analysis of results of the finite element modelling.
Design methods
942252 Grey system theory applied to rock mechanics. Technical note Cai Sijing; Tong Guangxu; Gao Hualin lnt J Rock Mech Min Sci V30, N4, Aug 1993, P473-478 The fundamentals of grey system theory, where a system is intermediate between a 'black box' (interior can be controlled but not observed) and a 'white box' (can be controlled and observed) are outlined. Grey relation analysis, tbr use when a system contains a number of parameters or factors whose interrelations are not very clear, is presented. The grey model for the examination of the mathematical relation between factors, grey system prediction, and grey decision making on the unity of event, countermeasure, and effect are described. Applications to rock engineering are briefly considered.
942253 Advanced scheduling in an opencast coal operation Simpson, H Quarry Manage Sept 1993, P23-33 Production at the Middleberg open pit coal mine in South Africa has been optimised by use of the MINESTAR Enhanced Scheduling Software Package. This program can model physical parameters and simulate production machinery. Primary short-term requirements and long-term schedules can be rapidly evaluated and a variety of options compared. The package has become a standard management tool.
942254 Reliability prediction around openings in Rock Engineering Huang Hongwei Proc EUROCK'93, Lisbon, 21-24 June 1993 V1, P129-134. Publ Rotterdam: A A Balkema, 1993 Because rock mass structures are uncertain, selection of input parameters for numerically modelling the stability of underground openings usually requires engineering judgement. An alternative approach is proposed, using in-situ measured displacements, Grey system forecasting (some rock mass parameters known, some unknown), Bayesian back analysis, and reliability analysis of the finite element method.
See also: 942439
942251 Establishing the potential behavioural modes of rock engineering systems by computer simulation of interaction matrix energy flux. Technical note Hudson, J A; Hudson, J L lnt J Rock Mech Min Sci V30, N4, Aug 1993, P457-468
942255 Practical aspects of a three-dimensional approach to tunnel data recording Howell, G C; Jooste, D E; Warwick, D W Proc TUNCON'92, Design and Construction of Tunnels, Maseru, Lesotho, September 1992 P157-162. Publ Yeoville: South African National Council on Tunnelling, 1992
The interaction matrix concept for rock engineering of Hudson (1992) is first outlined. Each leading diagonal box is associated with an energy potential and energy transfer via the mechanisms in the off-diagonal boxes is considered. A computer program has been developed to calculate and graphically display energy changes within the interaction matrix. Simulation cases are shown for regular and irregular attenuation and chaotic behaviour, with initialisation of primary variables then total step energy transfer and entropy increase for a number of steps illustrated. Practical applications of the concepts described are considered.
Use of computers in design of underground structures is now almost universal. Recent developments in 3D graphics capabilities and database programs combined with geometric design packages allow visual represenatation of many features. Traditional investigation methods have been modified for use with the new systems, for instance face mapping has been largely replaced by longwall mapping. A split map technique has been developed which allows accurate description of discontinuities without need to directly measure their dip and strike. The 3D graphic representations allow pertinent geological features to be studied at the design stage.